The present invention is directed to methods and devices for occluding a patient""s ascending aorta and returning oxygenated blood to the patient when the patient is supported by a bypass system. The invention is particularly useful when performing surgery on the heart and great vessels.
In conventional open heart surgery, the patient""s heart is accessed through a large opening in the patient""s chest, such as a median sternotomy. With the patient""s heart exposed, various catheters, cannulae and clamps are applied directly to the patient""s heart and great vessels. Blood is withdrawn from the patient through a venous cannula and returned to the patient through an arterial return cannula which is typically inserted through a pursestring suture in the ascending aorta. The heart is arrested by infusing a cardioplegic fluid into the ascending aorta with a needle. The ascending aorta is typically occluded with an external cross-clamp around the ascending aorta to isolate the coronary arteries from the remainder of the arterial system.
Recent developments in cardiac surgery have provided cannulae and catheters for occluding a patient""s ascending aorta, returning oxygenated blood to the patient, and delivering cardioplegic fluid to the patient without requiring direct access to the patient""s heart. Such systems are described in U.S. Pat. Nos. 5,584,803, 5,478,309 and Re. 35,352. The devices and methods described in these patents enable surgeons to perform various procedures on the patient""s heart and great vessels, such as bypass grafting and valve replacements, without requiring a large opening in the patient""s chest. Such procedures reduce the pain and trauma suffered by the patient as compared to traditional open-heart procedures.
Another advantage of the systems described in U.S. Pat. Nos. 5,584,803, 5,478,309 and Re. 35,352 is that occlusion of the aorta is accomplished with a balloon positioned in the aorta rather than an external clamp around the aorta. Use of a balloon to occlude the ascending aorta may reduce the amount of emboli released into the bloodstream as compared to external cross-clamps thereby reducing stroke incidents.
Although the systems described above enable a wide range of surgical procedures on a stopped heart, positioning of the aortic occlusion balloon is often challenging since the balloon must be positioned in a relatively small space between the aortic valve and brachiocephalic artery. Inadvertent occlusion of the brachiocephalic artery is dangerous since the right carotid artery, which branches off the brachiocephalic artery and provides blood to the patient""s brain, would also not receive oxygenated blood. Positioning of the balloon is particularly challenging when performing aortic valve procedures since the balloon must be positioned far enough from the aortic valve to permit the surgeon to perform the procedure on the aortic valve without interference from the balloon.
Thus, an object of the present invention is to provide an aortic occlusion catheter having an occluding member which may be easily positioned within a patient""s ascending aorta.
The present invention provides an aortic occlusion catheter and method of occluding a patient""s ascending aorta and delivering oxygenated blood to the patient from a bypass system. The aortic occlusion catheter is inserted through a penetration in the patient""s arterial system and passed through the junction between the brachiocephalic artery and ascending aorta. In a preferred embodiment, the aortic occlusion catheter preferably enters the patient""s arterial system through a penetration in the axillary or subclavian artery.
The aortic occlusion catheter has an occluding member which is positioned in the ascending aorta and expanded to occlude the patient""s ascending aorta thereby isolating the coronary arteries from the rest of the patient""s arterial system. The occluding member, which is preferably a balloon, is preferably attached to the catheter shaft along a portion between proximal and distal ends of the occluding member. When the occluding member is expanded, the occluding member expands toward one side of the shaft. In a preferred embodiment, the expanding side of the occluding member is positioned to expand toward the aortic valve.
The aortic occlusion catheter also has a blood flow lumen having first and second openings for returning oxygenated blood to the patient. The first and second openings are on opposite sides of the occluding member so that oxygenated blood is delivered to both sides of the occluding member. One of the openings provides oxygenated blood to arteries superior to the junction between the brachiocephalic artery and the aortic arch while the other opening provides oxygenated blood to the rest of the body. An advantage of providing openings on both sides of the occluding member is that occlusion of the brachiocephalic artery does not pose a risk to the patient since oxygenated blood is delivered to both sides of the occluding member. Another advantage of the aortic occlusion catheter is that the occluding member is easily positioned far from the aortic valve thereby maximizing the working space for performing aortic valve procedures.
The aortic occlusion catheter also preferably includes two pressure lumens for measuring pressure on both sides of the occluding member. Although two pressure lumens are preferred, only one pressure lumen may be necessary. The pressure lumens are coupled to a pressure monitor for measuring the blood pressure on both sides of the occluding member. The pressure monitor is used to prevent excessively high or low blood pressures and, in particular, excessively high blood pressure in the carotid arteries.
These and other features will become apparent from the following description of the preferred embodiment.